The aim of this proposal is to develop the capacity of a system of fertility measurement adapted to the potentialities and limitations of reproductive histories collected in fertility surveys, and designed in such a way that it serves simultaneously the purposes of analysis of the immediate effects of variations in such instrumental variables as the use and effectiveness of contraception, reproductive intentions with respect to the quantum and tempo of fertility, of length of lactation, and age at marriage, inter alia, and also the purposes of fertility projection, and thus the assessment of the consequences of reproductive change. The measurement system is distinctive in the level of specificity employed to characterize fertility (with respect to parity, age at entry into that parity, and length of time in that parity, as well as respondent's age), in the systematic exploitation for time series purposes of isomorphic parameters of real and synthetic birth cohort experience, and in the implementation of a systematic procedure for linking the overt age distribution of fertility with its basic determinants of successive selection in the progression of a birth cohort from lower to higher parities, with intervening interval lengths dependent on parity and age at entry into that parity. The projection capability is extended for the first time to permit direct linkage between behavioral assumptions and their reproductive consequences. From a standpoint of the scientific disciplines involved, the work is demographic and statistical. A precise and parsimonious description of reproductive behavior is directly related to the subject of health.